A large part of the medial temporal lobe consists of the hippocampal formations. Neuropathologic and clinical studies place atrophy in the hippocampal formations central in the processes related to the development of Alzheimer's disease (AD). Neuropathologic studies show that the hippocampal formations are among the first to be diseased by the two classic lesions in AD, neuritic plaques and tangles. The hippocampal formations are also involved in short and long term memory, disturbances in which are one of the sentinel cognitive signs of AD. Hippocampus formations have also been shown to be smaller in persons with AD compared to controls. This evidence has led to the proposal that hippocampal atrophy be used as an aid to the diagnosis of AD and a predictor of future AD. Because there is evidence from several different types of studies that the hippocampus plays a central role in the AD, examining risk factors for hippocampal atrophy may help to gain insight into the etiology of AD. As a putative intermediate step in the dementing process, research on risk factors for hippocampal atrophy may help to formulate possible interventions in the early stages of AD. To date studies of risk factors for hippocampal atrophy are limited to small studies of socio-economic correlates. We continue to make use of data from the Honolulu -Asia Aging Study to examine the to evaluate the differences in hippocampal shape in persons with no dementia, alzheimer's disease and vascular dementia.